Projectile



Sept. 19, 1961 H. F. DUNLAP ETAL 3,000,316

PROJECTILE Filed July 10, 1944 2 Sheets-Sheet 1 3 25 INVENTORS HENRY I". DUNLAP WILLIAM D. GROZIER 6 ROBi/Z MBLEAKIVE Y TORNEY Sept. 19, 1961 H. F. DUNLAP ETAL 3,000,316

PROJECTILE Filed July 10, 1944 2 Sheets-Sheet 2 HENRY Fl DUNLAP WILL/AM D. GROZIER GOBERTg BLEAgEY AT ORNEY United States Patent 3,000,316 PROJECTILE Henry F. Dunlap, William D. Crozier, and Robert M.

Bleakney, Albuquerque, N. Mex., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed July 10, 1944, Ser. No, 544,192 1 Claim. (Cl. 102-33) This invention relates to rotary sabot projectiles of the type which includes a subca-liber core having a substantially full caliber sabot for supporting and centering the core in a gun barrel and releasable from the core when the projectile emerges from the gun muzzle. More particularly, the invention has reference to a novel projectile of the character described in which the sabot is in the form of a ring threaded on the rear end portion of the core and releasable therefrom by centrifugal force.

One object of the invention resides in the provision of a sabot projectile having a subcaliber core, a substantially full caliber sabot threaded on the rear end portion of the core, and a turning band mounted on the sabot, the threads between the sabot and core being in such a direction that the sabot is tightened on the core by rotation of the turning hand through action of the gun rifling.

Another object of the invention is to provide a sabot projectile of the character described in which the threaded sabot is at least partially segmented by longitudinal, radial weakening cuts to facilitate fracturing of the turning band and release of the sabot under centrifugal force.

Still another object is to provide a sabot projectile of the character described in which the weakening cuts in the sabot are filled with a malleable material, such as copper, beaten into the cuts so as to seal the sabot against leakage of the powder gases and to resist loosening of the sabot on the core.

A further object of the invention is to provide a projectile comprising a subcaliber core having a substantially full caliber segmented sabot for supporting the turning band, the rear end portion of the sabot being tapered toward the base of the core so that the powder gases in the gun barrel exert a turning moment on the sabot segments which opposes the normal tendency of the gases to upset these segments.

An additional object of the invention is to provide a sabot projectile of the character described which is simple in construction, has relatively few parts, and may be easily assembled.

These and other objects of the invention may be better understood by reference to the accompanying drawings, in which FIG. 1 is a view in side a sabot projectile made in accordance with the invention;

FIG. 2 is a rear elevational view of the projectile shown in FIG. 1;

FIG. 3 is a sectional view on showing the bourrelet;

FIG. 4 is a side elevational view of the assembled bourrelet segments;

FIG. 5 is a view similar to form of the projectile;

FIG. 6 is a sectional view on the line 6-6 in FIG. 5;

FIG. 7 is a view in side elevation, partly in section, of another form of the projectile;

FIG. 8 is a sectional view on the line 8-8 of FIG. 7;

FIG. 9 is a view in side elevation, partly in section, of still another form of the projectile;

FIG. 10 is a sectional view on the line 1010 in FIG. 9;

FIG. 11 is a perspective view with part of the sabot illustrated in FIG. 9, showing details of the threads and the turning band groove, and

the line 3-3 in FIG. 1,

FIG. 1 showing a modified elevation, partly in section, of I FIG. 12 is a developed view of the turning band groove of the sabot illustrated in FIGS. 9 and 11.

Referring to the drawings, the projectile shown in FIGS. 1 through 4 comprises a subcaliber steel core 10 having an ogive 10a and an annular groove 11 near the ogive and in which a substantially full caliber bourrelet 12 is mounted. The bourrelet, as shown, comprises a plurality of segments 13 fitted closely together and seated in the groove 11 to form a ring-like structure on the core.- At its front end, the bourrelet is formed with an annular recess 13a in the periphery of the bourrelet, the recess being partly defined by a shoulder 14. The bourreletsegrnents 13 are held closely together in the groove 11 by a retaining ring 15 fitted tightly in the groove 13a and engaging the. shoulder 14. The ring being shrunk or otherwise mounted on the bourrelet. The bourrelet segments 13 and the retaining ring 15 may be made of steel or other suitable material. I

At its rear end portion, the core 10 is externally threaded, as shown at 17. A sabot 18, which maybe made of steel, is screwed on the thread 17 and tightened against the front end of the thread course. The sabot 18 is in the form of a ring having substantially full caliber dimension and partially segmented by longitudinal, radial slots 19 extending from the rear end of the sabot but terminating short of its front end. The slots 19, as shown, radiate from the inner diameter or threaded portion of the sabot but terminate short of the outer surface of the sabot. In order to seal the sabot against leakage of gas through the slots 19, we provide suitable seals 20 inv the front ends of the slots. Preferably, the seals 20 comprise amalleable metal, such as copper, which is beaten into the slots so as to fill completely the rear ends thereof. In this connection, it will be observed that the seals 20, in their final form, are wedged into the threads 17 on the core and serve to resist loosening or unscrewing of the sabot on the core, A turning band 21, which may be made of annealed copper, is mounted on the forward portion of the sabot 18 and supplements the uncut portions of the sabot in holding the segments together on the threaded portion 17 of the core.

The rear or trailing end portion of sabot 18 is tapered sharply fromthe turning band 21 to the base of the projectile. Accordingly, the outer peripheral surface of the sabot is of generally frusto-conical form with its reduced end adjacent the base of the core.

In operation, when the projectile is fired from the gun, the high pressure from the powder propellant acts upon the base of the core 10 and also upon the rear ends of the sabot and the turning band. As the projectile moves through the gun barrel, the turning band 21 is engraved by the usual rifiing in the barrel to impart rotation to the core 10 through the sabot. The torque transmitted from the turning band to the sabot acts to tighten the sabot against the front end of the thread course 17 on the core, whereby rotation of the band is transmitted to the core without lost motion between the parts. Also, the

' seals 20 in the sabot slots 19, by reason of theirclose engagement with the core thread 17, form a thread look to oppose rotation of the sabot relative to the core during transmission of this torque. During movement of the projectile along the gun barrel, the core 10 is supported and centered in the barrel by the bourrelet 12 and the sabot 18, and the latter are held on the core by the confining effect of the gun barrel, against the action of centrifugal force incident to the high speed rotation of the projectile.

When the projectile emerges from the gun muzzle and is thereby released from the confining effect of the gun barrel, the bourrelet ring 15 and turning band 21 are fractured under the centrifugal force, whereby the bourrelet and sabot are released from the core. The core,

therefore, proceeds along its trajectory without the aerodynamic drag which would otherwise be imposed upon it by the bourrelet and the sabot. The ring 15 is broken partly by the action of centrifugal force on its own mass and partly by the radial force to which it is subjected by the bourrelet segments. It will be understood that the sabot 18 is fractured by the centrifugal force at the weakened portions adjacent slots 19, the shattering of the sabot being augmented by the reaction or counter-fiexure of the sabot segments when relieved at the muzzle of the erstwhile powder gas pressure. The release of the hourrelet and sabot from the core occurs immediately upon emergence of the projectile from the gun barrel and is effected with a relatively low energy loss and without substantial interference with the flight of the projectile core.

It will be observed that the slots 19 partially divide the sabot into longitudinal segments, each of which acts substantially as a cantilever beam radiating from the threaded core portion 17. The powder pressure in the gun barrel normally exerts a turning moment on these segment beams tending to upset them so that their outer ends fold forwardly on the core. However, with the new construction, by reason of the frusto-conical form of the rear portion of the sabot, the powder gases exert on the periphery of the sabot segments adjacent their rear ends a turning moment which opposes the turning moment previously described. In other words, the effect of the powder pressure on the frusto-conical portions of the sabot segments is to force or flex the rear end portions of the segments inwardly against the threads 17 on the core, causing the threads to bear deeply into each other, thereby resisting the tendency of the powder pressure to upset the segments. Also, the gun barrel in eifect exerts a radial thrust inwardly on the turning band 21 which resists the turning moment acting to upset the segments.

The projectile shown in FIGS. and 6 comprises a subcaliber steel core 23 having a nose 24 and a threaded portion 24a directly to the rear of the nose. A wind cap 25, which may be made of aluminum, is screwed on the threaded portion 24a and tightened against the shoulder at the rear end of the threaded portion. A sleeve-like bourrelet 26 of substantitally full caliber dimension is closely fitted on the intermediate portion of the core. The bourrelet 26 may be made of steel, plastic, or other suitable material and is provided with a plurality of longitudinal weakening cuts 27 radiating from the inner diameter of the bourrelet but terminating short of its outer diameter.

To the rear of the bourrelet 26, the core 23 is externally threaded, as shown at 23a. A steel sabot 29, similar to the sabot 18, is screwed on the threaded portion 23a and tightened against the rear end of bourrelet 26. The sabot 29 has longitudinal slots 30 extending therethrough and radiating from the threads 23a so as to partially segment the sabot. The slots 30 are sealed by copper or other malleable metal 31 beaten into the rear end of the slots and forced into the threads 23a. A turning band 32 is mounted on the front end portion of the sabot and may be provided with internal tongues SZa-press-fitted into annular grooves in the sabot to resist stripping of the band from the sabot when the projectile is fired from the gun. The rear end portion of the sabot 29 is tapered toward the base of the projectile core, as described in connection with the projectile shown in FIG. 1.

The operation of the projectile shown in FIGS. 5 and 6 is generally similar to that of the projectile illustrated in FIG. 1. However, the bourrelet 26 is held in position on the core 23 by its tight fit around the cylindrical surface of the core and also by engagement with the front face of the sabot, so that it is unnecessary to provide an annular groove or other positive means for securing the bourrelet. It will be understood that the bourrelet 26 is released from the core by fracturing of the bourrelet 4 adjacent the radial cuts 27 under centrifugal force when the projectile emerges from the gun muzzle.

Referring to FIGS. 7 and 8, the projectile there shown comprises a subcaliber core 34 carrying a substantially full caliber sleeve-like bourrelet 35 provided with longitudinal radial cuts 36 for partially segmenting the bour relet. The cuts 36 radiate from the inner diameter of the bourrelet but terminate short of its outer diameter so as to leave uncut portions 3501 holding the segments together on the core.

The rear end portion of the core 34 is externally threaded, as shown at 38, and a sabot 39 of ring-like form is screwed on the threaded portion 38. The sabot may be made of steel or other suitable material and has a plurality of longitudinal slots 39a extending through it, the slots being sealed by copper or other malleable metal 40 beaten into the rear ends of the slots and against the threads 38. A turning band 41 is fitted closely around the sabot and has internal tongues 41a disposed in annular grooves in the peripheral portion of the sabot. As shown at 35b, the front end of the sabot 39 is tapered sharply and -fits closely against a complementary surface on the rear end of the bourrelet.

When the projectile shown in FIGS. 7 and 8 1s fired from a gun, the torque incident to rotation of the turning band 41 by the gun rifling acts to tighten the sabot 39 against the front end of the thread course 38 on the core and against the rear end of bourrelet 35, whereby rotation of the turning band is transmitted to the core without lost motion. As the projectile is accelerated in the gun barrel, the resulting force of setback of the bourreletsleeve 35 against the sabot 39 acts to oppose the previously described tendency of the powder gases to upset the sabot segments. When the projectile emerges from the gun muzzle, the uncut portions 35a of the bourrelet are fractured by the centrifugal force due to the hlgh speed rotation of the projectile, so that the bourrelet is released from the core. Also, the turning band 41 is broken by the centrifugal force, and the sabot is released by fracturing of its uncut portions under the action of the centrifugal force.

The projectile shown in FIGS. 9 through 12 comprises a subcaliber core 43 and a sleeve-like bourrelet 44 fitted closely around the .core intermediate its ends. The bourrelet 44 has a plurality of longitudinal radial weakening cuts 45 which partially segment the bourrelet. On ns rear end portion, the core has a thread course '47 on which a sabot 48 is screwed. The sabot is PIOVIdCd WIlIh longitudinal weakening cuts 48a radiating from its 1111161 diameter to its outer diameter and dividing the sabot into longitudinal segments which are held together by an uncut portion of the sabot at its rear end. Intermediate its ends, the sabot has an annular external groove 49, the bottom of which is scored as shown at 50. A turning band 51 is mounted in the groove 4-9 and fitted tightly agamst the scored bottom 50 of the groove.

The operation of the projectile shown in 9 through 11 is generally similar to that of the pro ectile illustrated in FIG. 7. It will be observed, however, that in the projectile shown in FIG. 9, it is not necessary to provide seals for the longitudinal weaken ng cuts 48a m the sabot, since the rear end portion of the sabot 1s uncut. The breaking of the uncut portion of the sabot is aided by the cantilever action of the sabot segments under centrifugal force on the front portions of the segments. Also, by .reason of the scoring 50 on the bottom of the sabot groove 49, the turning band is prevented from rotatlng relative to the sabot under the action of the rifling as the projectile is accelerated through the gun barrel.

The new projectile, in its various illustrated forms, is simple and compact in construction, has relatively few parts, and may be easily assembled. The sabot and bourrelet provide efiicient supporting and centering means for the subcaliber core in the gun barrel and are quickly and positively released from the core by centrifugal force as soon as the projectile emerges from the gun muzzle, with relatively low energy loss and without substantially interfering with the flight stability of the core.

We claim:

In a projectile, a suboaliber core having an external thread course, means for centering the core in an oversize gun barrel, said means consisting of an internally threaded sabot which is screwed onto the thread course, said sabot being at least partially slotted to insure its shattering when eventually yielding to centrifugal force, and a malleable filler forced into the slots and extruding into part of the thread course, respectively sealing the slots against gas escape and locking the sabot on said core.

References Cited in the file of this patent UNITED STATES PATENTS Rollins Jan. 28, Brandt Sept. 11, Fornaci Nov. 19,

FOREIGN PATENTS 

